This document specifies a method for determining the amount of certain benzotriazole compounds (UV-320, UV-327, UV-328, UV-350) in textiles by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) or liquid chromatography-diode array detector (LC-DAD) or gas chromatography with mass spectrometry (GC-MS). The method is applicable to all kinds of textile materials (fibres and fabrics).